On 10/14/2011 04:01 PM, Stephen Warren wrote: > Nicolas Pitre wrote at Friday, October 14, 2011 2:45 PM: >> On Fri, 14 Oct 2011, Stephen Warren wrote: > ... >>> I did originally briefly look into getting U-Boot to boot a zImage, but >>> that looked like a far more invasive patch. There were rumours of some >>> chip's custom U-Boot already having such support, but I couldn't find >>> it, nor any evidence of such support in mainline U-Boot. >> >> FRom my clone of the u-Boot repo: >> >> $ git grep -l zImage >> README >> arch/sh/lib/zimageboot.c >> arch/x86/lib/zimage.c >> ... >> >> Even the name of some of those files clearly hints zImage support. >> >> In any case, loading zImage should be even simpler than loading uImage. >> It is the same as loading uImage except that you just have to skip the >> checking and relocating steps. > > Just by way of background in case anyone is wondering why I wrote the > patch I did: > > Those files both implement custom commands "zimageboot" and "zboot". I > was looking for integration with the existing "bootm" command. > > The advantage of re-using "bootm" for this is that it already supports > all the stuff like setting up kernel command-lines, initrds, knowing how > to pass the FDT to the kernel, and whatever other OS-specific setup might > be required. > > The disadvantage of adding zImage support to bootm is that I'd have to > teach a bunch of U-Boot image handling code about a new image format; it > already knows about "legacy uImage", "FIT" images, and I'd have to add a > third "zImage" format. Doing so would at least require adding a lot of > "case IMAGE_FORMAT_ZIMAGE" everywhere, but it'd probably be best to add > some kind of vtable for image formats to move all the image-format > knowledge into format-specific files, leaving the users of the images > with much smaller code. > > I didn't feel like making such a large change. Hence, I chose to make a > small change to the existing uImage support. > > Now admittedly I did say I didn't find any traces of zImage support, which > isn't what I'm saying here; I guess I forgot about the stuff I did find > soon after I chose the path of modifying the uImage formats. > FYI, this exact topic has been discussed on the Linaro weekly boot-architecture call and list. The discussion has been more general in terms of what can be done to make installing and updating kernels easier/work for distros. https://wiki.linaro.org/OfficeofCTO/BootArchitecture Rob -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
